example for using stencil buffer to draw highlight

**Describe the bug**
Hello, it's nice to see stencil buffer is in the newer version of filament. could you please provide an example to use that to draw highlight? Thanks

The issue names no files, tests, or entry points. First clarify which supported backend and example target should demonstrate stencil-based highlighting, then inspect existing rendering examples and define a reproducible validation path; done means a documented example that shows the requested effect.

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